1. Field of the Invention
The instant invention relates to an apparatus and method for testing numerous actuators, and more particularly to the testing and evaluation of actuators having different load characteristics.
2. Description of the Prior Art
Actuators, are devices which are typically utilized for the positioning of a load or loads under control. These devices are used in a multitude of applications, for example, on ships for navigational and stabilization control, on construction equipment, on aircraft, and on rocket engine nozzles. One specific example of the use of load actuators is for the proper positioning of a rocket engine nozzles to deflect exhaust gases from the rocket engines to control the flight trajectory of propulsion vehicles. During a vehicle's flight a myriad of forces act to oppose the deflection of the engine nozzle. These forces are a function of many parameters including, but not limited to the position of the nozzle deflection with respect to the flow of engine nozzle exhaust gases, the rate of change of the nozzle deflection and the effects of mass inertia on the acceleration of the nozzle deflection. The controlled positioning of the engine nozzle via a load actuator in response to the forces acting upon it is clearly indispensable to maintenance of the desired trajectory of a propulsion vehicle. Similarly, by way of another example, actuators utilized in nautical environments must be capable of contending with the effects of the forces of water along the control surfaces of a ship's rudder, or other like devices. These hydraulic forces are typically counteracted by the actuator to obtain the desired navigational results.
It is desirable to test actuator designs prior to their use to ensure that the actuator will meet operational requirements. An untested actuator may jeopardize the reliability of an expensive propulsion system and its associated payloads, or may even result in the destruction of aircraft. Heretofore, load actuator simulators were constructed utilizing passive load elements. These test devices, normally bulky and expensive to manufacture, would produce a force proportional to a known actuator position, using a very stiff spring element. A force proportional to the actuator acceleration would also be generated using a predefined weight or mass. The spring element, heretofore, typically employed was a stiff metal column of considerable diameter and length that acted like a spring against which an actuator was attached for purposes of testing. These prior art testing devices were designed for a fixed set of known operational conditions, and thereby were not easily changeable if and when a system's design changed. Furthermore, these passive prior art devices failed to simulate critical real time forces such as nozzle friction loads which, at varying times, become major load factors in particular actuator applications.
From the foregoing, the need should be appreciated for a new and improved actuator load simulator having a means for testing a variety of different actuators without the need for an expensive custom designed test apparatus whose usefulness is limited to a particular design or set of fixed operational conditions. Accordingly, a fuller understanding of the invention may be obtained by referring to the SUMMARY OF THE INVENTION, and the detailed Description of the Preferred Embodiment, in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.